Cronyism is the practice of partiality in awarding jobs and other advantages to friends or trusted colleagues, especially in politics and between politicians and supportive organizations. For instance, this includes appointing "cronies" to positions of authority, regardless of their qualifications; an example of this can be found here, this is in contrast to meritocracy, in which appointments are made purely on qualification.
Cronyism exists when the appointer and the beneficiary (such as an appointee) are in social or business contact. Often, the appointer needs support in their own proposal, job or position of authority, and for this reason the appointer appoints individuals who will not try to weaken their proposals, vote against issues, or express views contrary to those of the appointer.
Politically, "cronyism" is derogatorily used to imply buying and selling favors, such as: votes in legislative bodies, as doing favors to organizations, giving desirable ambassadorships to exotic places, etc. Whereas cronyism refers to partiality to a partner or friend, nepotism is the granting of favour to relatives.